1. Field
This specification relates to separating and recovering of high purity tellurium (Te) for recycle which is a high-priced metallic element, from a solution in which a material containing tellurium such as a thermoelectric material containing Bi2Te3 is dissolved, using a solvent extraction method.
2. Background
Thermoelectric materials are a type of semiconductor material, which has a function of converting electric energy into thermal energy or thermal energy into electric energy.
With improvement of income levels, demands on refrigerating and cooling drinking water or various types of daily necessaries are highly increasing in hot humid summer weather like South Korea. To meet such expectations, supply of electric home appliances such as a hot and cold water dispenser and a small refrigerator are remarkably increasing around us. An essential component for electric home appliances having the refrigerating and cooling function is a thermoelectric module which can move heat from one side to other side by receiving electric energy.
Among those thermoelectric materials, Bi2Te3 is used the most widely. It is known that the thermoelectric material has a lifespan of about 10 years. Tellurium (Te) which is an element of the thermoelectric material Bi2T3 is one of very rare metals and thus is very expensive. Therefore, it is necessary to recycle the tellurium from a waste thermoelectric module.
When the waste thermoelectric module is dissolved with hydrochloric acid, nitric acid or combination thereof for recycle, the solution may contain small amounts of Cu, Ni, Sn and Sb in addition to Bi and Te. Therefore, in order to recover tellurium as a high purity metal from the acidic solution, it may be first carried out to separate the tellurium from the other metallic elements.
As widely known, a separation of metallic elements from an aqueous solution may be carried out by precipitation, ion exchange, solvent extraction and the like. Among others, the precipitation method has an advantage in low cost but also has a difficulty in a high degree of separation of each metallic element. Also, the ion exchange method uses a cation-exchange resin or an anion-exchange resin so as to very effectively separate the metallic elements from the aqueous solution, but also has disadvantages in a high price of the anion-exchange resin and a low separation speed.
Therefore, the present disclosure proposes a solvent extraction method for recycling tellurium by separating the tellurium from a solution, which is obtained by dissolving a Bi2Te3-based waste thermoelectric module, in a very effective and economical manner.